Body fluids, Risk of Infections, and Their Importance
Route of infections:
- Many body fluids, including blood, are infectious and hazardous materials for human beings, particularly people working in the laboratory.
- These biological hazards expose unprotected laboratory workers to bacteria, viruses, parasites, and other biological agents.
- This infection may be from ingestion, inhalation, inoculation, or tactile contacts. There may be inhalation of the infectious material from the patient or their body fluids/tissues.
The source of contamination may be from:
- Contaminated laboratory equipment.
- Improperly processed blood products.
- Inappropriate disposal of laboratory waste products.
- The potentially infectious body fluids are:
- Bloody fluids.
- Pleural fluid.
- Pericardial fluid.
- Peritoneal fluid (ascites).
- Amniotic fluid.
- Cerebrospinal fluid.
- Vaginal secretions.
- Saliva in a dental procedure.
- Synovial fluid.
- Pus and purulent discharge.
- Tissue biopsy or organ which is unfixed.
- Noninfectious material is:
- Nasal secretion.
- Stool. Tears.
Importance of various body fluids:
- Salivary glands produce one liter of fluid /day.
- Some of the drugs can be monitored like Digoxin, Phenytoin, Theophylline, Phenobarbitol, and dexamethasone.
- Drugs of abuse can also be monitored like alcohol, barbiturates, amphetamines, and marijuana.
- The hormone can also be measured like progesterone, 17-alpha-hydroxyprogesterone, and cortisol.
- In the diagnosis of Sjogren’s syndrome, can measure increased Na+ and chloride.
- Can estimate secretory IgA.
- It helps to diagnose allergy by showing an increased number of eosinophils.
- An increased number of polys indicates acute infection.
- Can detect RSV by rapid antigen test.
- It will differentiate between nasal sections and CSF in a possible skull fracture.
- The usefulness of the sputum culture is controversial.
- Mostly the sputum is contaminated by the upper respiratory tract bacteria.
- Some contaminants are staphylococcus aureus, streptococcus pneumonia, Hemophilus influenza, enteric gram-negative organisms, and candida.
- In literature, there is a dispute that sputum culture may find the causative agent.
- In case if a pure growth of the organism is found to favor the pathogenic infection.
- In case of the increased number of squamous cells, favor the contamination by oropharyngeal mucose.
- The more squamous epithelial cells are found, the more chances for contamination.
- The number of tears may decrease in Sjogren syndrome, dehydration, decreased facial nerve function, and Horner syndrome.
- Lysosomal diseases may be diagnosed by the deficiency of enzyme deficiency in the tears. The following diseases are diagnosed:
- Tay-Sachs disease.
- Type II glycogenesis.
- Metachromatic leukodystrophy.
- Fabry disease.
- Sandhoff disease.
- If there are increased WBCs in the milk, that will indicate acute infection.
- >103 colonies of the bacteria/mL indicate infections compared to the noninfectious inflammation or clogged ducts.
Cerebrospinal fluid (CSF):
- CSF may be the cause of bacterial or viral meningitis.
- In infants under the age of 1 to 2 months have the most common infection by B streptococci.
- Children from 3 years to 5 or 6 years have H.Influenzae commonest organism followed by meningococci and pneumococci.
- Children and older adults have meningococcal meningitis and the second common organism is pneumococci.
- In older people, pneumococci are more common than meningococci.
- CNS syphilis can also be seen and diagnosed through CSF examination.
- Mycobacterial meningitis is common in children between the age of 6 months and5 years. It is also seen in elderly patients.
- Cryptococcal meningitis is the most common fungus-producing CNS infection. Other fungi causing CNS infections are Candida, blastomycosis, histoplasmosis, and coccidioidomycosis.
- HIV also produces mild aseptic meningitis.
Ascites may be seen in:
- Chronic liver disease = 81%
- Malignancies = 10%
- Congestive heart failure = 3%.
- Tuberculous ascites = 1.7%.
- Patients with dialysis = 1.0%.
- Gram stain of the ascitic fluid shows few bacteria by spontaneous peritonitis, but many are due to intestinal perforation.
- This may be seen in tuberculosis and gram-negative bacteria like Klebsiella, E.coli, and other gram-negative bacteria.
- Gram-positive bacteria, especially streptococci, may see this.
- The most common cause of the pleural effusion is congestive heart failure and malignancies.
- Infections like tuberculosis and pneumonia are the third common causes.
- Try to differentiate the chylous effusion, which is usually due to increased triglycerides.
- Pleural fluid CEA level may be increased in various malignancies and few benign conditions.
- Pericardial effusion may develop due to active rheumatic fever in 40% of the cases.
- Bacterial infection leading to pericardial effusion is seen due to tuberculosis, streptococcus pneumonia, staphylococcal, and gram-negative bacilli.
- Other infections may be due to Coxsackie B, rickettsial parasites, mycobacteria, and fungi.
- The most common cause is viruses.
- Rarely this may develop in severe anemia, scleroderma, polyarteritis nodosa, Wegener granulomatosis, rheumatoid arthritis, radiation, mycotic infections, and idiopathic.
- There may be infection by chlamydia and syphilis.
- The presence of the inflammatory cells indicates genitourinary infections.
- The most common organisms are E.coli.
- The viruses can also live in the semen like Ebola, HIV, hepatitis B, HCV, and herpes.
- Chronic infections affect the sperm count and lead to infertility.
- Trichomonas causing vaginitis is quite common. Freshly prepared PAP smear sensitivity is 50% to 70%.
- Bacterial infection of the vagina may be due to aerobic and anaerobic organisms.
- There may be infection fromG. vaginalis and Mobilucus accompanied by lactobacillus.
- Local causes may be endocrine, poor hygiene, scabies, pinworms, foreign bodies, and local irritants.
- There may be infection by the N. gonorrhea, Chlamydia, streptococcus group A, staphylococcus aureus, and idiopathic associated with HIV.
- Nearly 1 mL of the synovial is aspirated for the culture and other studies.
- Gram stain reported 40% to 70% positive in septic arthritis.
- Gram-positive organisms are more common than gram-negative bacteria.
- Gonococcal infection is the most common cause.
- Occasionally synovial RA test is positive before the serum.
- Lactate is raised in septic arthritis and is >250 mg/dL.
- Complement is lowered in rheumatoid arthritis and SLE.
- This is important for the diagnosis of various diseases.
- There is a change in the electrolytes in cystic fibrosis.
- There is different odor in various diseases like maple syrup disease, and some of the drugs.
- Sweat color is also important in various diseases like brown in ochronosis, red in rifampin (overdose), and blue in occupational exposure to copper.
- Stool examination is one of the noninvasive procedures to diagnose various diseases.
- The stool can be culture to diagnose bacterial diseases like salmonella, shigella, and tuberculosis.
- A stool examination can be done to diagnose parasitic infestation.
- A stool examination can diagnose viral diseases.
- The urinary tract infection (UTI) most common organism is E.coli.
- Nitrite test dispositive in UTI.
- Nitrite-negative organisms are enterococci, N.gonorrhea, and M. tuberculosis.
- Ear discharge is also called otorrhea.
- A middle ear infection may be bacterial or viral.
- Ear discharge may be seen in the ruptured eardrum.
- Other causes for ear discharge are swimming, foreign objects, wax, and trauma.